Being Alike Does Not Predict Happier Friendships

When Hyewon Yang, a recent psychology doctoral graduate from Michigan State University, finished analyzing personality scores from groups of friends, she offered a plain summary of what she had learned.

“Importantly, neither actual nor perceived personality similarity between friends predicted how satisfied they were with their friendships,” Yang said. “Rather, people’s own personalities and their perceptions of their friends’ personalities were more relevant to friendship satisfaction.”

Yang found that friends do tend to be slightly alike. With the exception of extraversion, meaning how outgoing or reserved a person is, friends showed small overlaps in personality. People also generally imagined that friends matched their own personalities more than the scores showed.

To test whether that matching mattered, Yang and her colleagues used statistical models designed to detect a specific jump in happiness when two friends had an identical score on a trait. The results showed no sign of such a jump, whether the similarity was real or only perceived. In other words, a close match on paper did not mean a closer friendship. These links were correlations from a single snapshot in time, not proof that traits cause happiness.

What did matter was the level of positive traits. Yang found that people who were kind, reliable, outgoing, and calm, traits psychologists call agreeableness, conscientiousness, extraversion, and emotional stability, meaning low neuroticism, tended to feel happier about their friendships overall. Friends described as especially kind and dependable were also regularly tied to stronger friendship happiness. Calm and cooperative friends tend to support a calmer and more enjoyable social life.

Yang also found that how you see a friend lined up with contentment more closely than how that friend sees themselves. Seeing a friend as loyal, open, and agreeable went along with feeling content in the friendship. Here predicted means correlated, not caused.

The study has clear limits. “Our study focused specifically on personality similarity among friends, and our sample consisted largely of same-gender friends, especially women, who were relatively young and close to one another,” Yang said. Because the data capture one moment, they cannot show whether similar personalities helped form the friendships, or whether friends gradually grew alike over years together.